Genetic ablation of V2a ipsilateral interneurons disrupts left-right locomotor coordination in mammalian spinal cord.
The initiation and coordination of activity in limb muscles are the main functions of neural circuits that control locomotion. Commissural neurons connect locomotor circuits on the two sides of the spinal cord, and represent the known neural substrate for left-right coordination. Here we demonstrate that a group of ipsilateral interneurons, V2a interneurons, plays an essential role in the control of left-right alternation. In the absence of V2a interneurons, the spinal cord fails to exhibit consistent left-right alternation. Locomotor burst activity shows increased variability, but flexor-extensor coordination is unaffected. Anatomical tracing studies reveal a direct excitatory input of V2a interneurons onto commissural interneurons, including a set of molecularly defined V0 neurons that drive left-right alternation. Our findings imply that the neural substrate for left-right coordination consists of at least two components; commissural neurons and a class of ipsilateral interneurons that activate commissural pathways.
Crone
Steven A
SA
Department of Neurobiology, University of Chicago, Chicago, IL 60637, USA.
Quinlan
Katharina A
KA
Zagoraiou
Laskaro
L
Droho
Steven
S
Restrepo
Carlos Ernesto
CE
Lundfald
Line
L
Endo
Toshiaki
T
Setlak
Jennifer
J
Jessell
Thomas M
TM
Kiehn
Ole
O
Sharma
Kamal
K
D000344:Afferent Pathways / Q000502:physiology; D000818:Animals; D004558:Electric Stimulation / Q000379:methods; D005260:Female; D007839:Functional Laterality / Q000235:genetics / Q000502:physiology*; D017353:Gene Deletion; D018398:Homeodomain Proteins / Q000235:genetics; D007395:Interneurons / Q000502:physiology*; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D008822:Mice, Transgenic; D009043:Motor Activity / Q000235:genetics / Q000502:physiology*; D011597:Psychomotor Performance / Q000502:physiology; D011995:Recombination, Genetic; D013116:Spinal Cord / Q000502:physiology*; D014157:Transcription Factors / Q000172:deficiency / Q000235:genetics
D018398:Homeodomain Proteins; D014157:Transcription Factors; C088975:Vsx2 protein, mouse